1. Field of the Invention
The present invention relates to a display device, and more particularly, to a flexible display and the method for forming an align key of the same, the flexible display which includes an alignment key required to align positions between film layers.
2. Discussion of the Related Art
With the recent trend to the information society, displays have the attentions as information transmitters. To use the displays in various fields, it is necessary for the displays to realize the low power consumption, the thin profile, the lightness in weight, and the high resolution.
The displays may be classified into a luminous type and a non-luminous type, wherein the luminous type displays correspond to an electro-luminescence (EL) display, a vacuum fluorescent display (VFD), and a plasma display panel (PDP); and the non-luminous type display corresponds to a liquid crystal display (LCD).
In recent days, a flexible display is beginning to make its appearance, which can be kept folded or rolled without any damages.
Even if various problems occurs in the recent flexible displays, the flexible display technologies are applied to the various displays using a thin film transistor (TFT) LCD device, an organic light-emitting diode (OLED), and a electrophoretic display.
In addition to the above-mentioned flexible display using the complex structure, the simple structure flexible display is also studied and researched.
Hereinafter, a related art flexible display will be explained with reference to the accompanying drawings.
FIGS. 1A and 1B are illustrating photographs of a related art flexible display.
As shown in FIGS. 1A and 1B, the flexible display is generally referred to as a scroll display. The flexible display is formed with a thin plastic substrate, which can be kept folded or rolled without damages. In this respect, the flexible display is one of next-generation displays. Up to date, the flexible display is applied to the OLED or the LCD in that the OLED or the LCD can be fabricated by the thin profile below 1 mm.
The OLED can emit the light in itself, and can obtain the good visibility in the dark surroundings as well as the bright surroundings. Among the nowadays-used displays, the OLED has the most rapid response speed which is one of most important standards to judge the function of mobile display.
Also, the OLED can be used to mobile devices, for example, mobile phones which can be designed with the ultra-thin profile. To realize the flexible display using the OLED, it necessarily uses the flexible substrate of plastic.
However, the related art flexible display has the following disadvantages.
Contrary to a common organic light emitting device, which is easy to form a thin film transistor (TFT) array or an organic emitting layer etc. with an alignment key formed on a transparent glass substrate, the flexible display is difficult to form forming layers since an alignment key is formed on the opaque plastic substrate and the alignment key is not visible in the process of align, therefore an alignment of positions between forming layers is not well done.
FIG. 2 is a cross section view for aligning the common glass substrate, FIG. 3 is an enlarged view long ‘A’ region of FIG. 2 and FIG. 4 is an illustrated figure in the process of observing ‘A’ region of FIG. 3 using a vision camera.
In the case of a common organic light emitting device when forming an organic emitting layer, as shown in FIG. 2 to FIG. 4, an alignment key 21 is formed at an edge of the substrate on the transparent glass substrate 20, and a vision camera is disposed corresponding to the edge of the substrate, and a shadow mask is disposed under the glass substrate and a source of an organic emitting material under the shadow mask 30.
In this case, corresponding to the alignment key of glass substrate, a mask alignment hole 35 is formed on the shadow mask 30, the vision camera 10 observes the detected region corresponding to the alignment key 21 and detects the degree of an alignment between the glass substrate 20 and shadow mask 30. In the shadow mask 30, a light shielding part 40 is defined at an outer portion of the alignment hole 35.
The related art flexible display has the following disadvantages.
However, the flexible display including the metal substrate, as shown in FIG. 2, since the metal substrate is made of an opaque material, in the case that the vision camera is disposed above the flexible display and the shadow mask is disposed under the flexible display, it is impossible to detect the alignment key using the vision camera.